One of the most important requirements of the next-generation wireless communication system is to support requirements for a high data transfer rate. To this end, research is being carried out on various technologies, such as Multiple Input Multiple Output (MIMO) and Cooperative Multiple Point transmission (CoMP), and a relay, but the most basic and stable solution is to increase the bandwidth.
However, frequency resources are now in the saturation state, and various technologies are partially being used in wide-ranging frequency bands. For this reason, as a scheme for securing a wide bandwidth in order to satisfy requirements for a higher data transfer rate, a Carrier Aggregation (CA) having a concept that each of scattered bands is designed to satisfy a basic requirement capable of operating an independent system and a number of bands are bundled into one system is being introduced. Here, a band that may be independently operated is defined as a Component Carrier (CC).
In a recent communication standard, for example, a standard, such as 3GPP LTE-A or 802.16m, the extension of a 20 MHz or higher bandwidth is taken into consideration. In this case, a broadband is supported by aggregating one or more CCs. For example, if one CC corresponds to a bandwidth of 5 MHz, a bandwidth of a maximum of 20 MHz is supported by aggregating four carriers. A system using a CA as described above is called a multi-carrier system.
In a multi-carrier system, a plurality of CCs can be used in downlink and uplink. Accordingly, a plurality of downlink grants for a plurality of downlink CCs (DL CCs) can be transmitted. The DL grant can include a scheduling message for each DL CC and a Transmission Power Field (TPC) for an uplink channel. In a multi-carrier system, however, although a plurality of uplink CCs (UL CCs) is configured in a mobile station, an uplink control channel can be transmitted through only one UL CC. In this case, if TPC fields included in the plurality of DL grants have different values, there is a problem in that a mobile station will determine transmission power for the uplink control channel using what method.
In a multi-carrier system, there is a need for a method of a mobile station controlling the transmission power of an uplink control channel and a mobile station using the method.